High octane, bad fuel pump?, great races

[3uromid]

Hello everybody!

Quick Background: I recently threw K04's @ 26 psi and my setup has been running perfectly. I have 2 tunes on the car (91 and 93) or which the car has always been ran on 91. A couple days ago I was passing a high octane gas station with my gas light just turning on so I decided to pull in and see If they had 93. Turns out they had 94 and I figured if I put about a half tank of 94 mixed with the remaining 91 it should balance out near 93...?

Car drove well for a quarter tank, even got a couple good runs with a JHM SC S5 (check out the videos below thx Kelvin).

Yesterday, a 2015ish Saleen 302 SC pulled up to me and we did a couple pulls but my car began to hickup WOT. I didn't think much of it as it was very minimal and not very noticeable. Pushed it a little more and became more noticeable. When idling the car seems to have a misfire although when stationary and revving (not on boost) the car doesn't seems to misfire. WOT the bar bogs like crazy but will still pull the whole way through the gear pretty quickly.

I figured to run the car nearly dry (ended up running it dry and was stuck on the freeway) to fill it up with 91 again and run my 91 tune.

The bogging is still there.

I'm thinking my fuel pump went is giving out (yes i'm running the stock fuel pump). I did a quick search through the forums and see many different symptoms for fuel pump failure. Any way to test the fuel pump? Any other ideas of what it could be?

I haven't ran any codes but as soon as I do I'll get them up.

Thx in advance




Enjoy the videos:

https://youtu.be/poPXu9RtIBg

https://youtu.be/ioQeNk1ETwc

https://youtu.be/Ggq2mWjsJes

[jimmer009]

Ko4's @ 26psi is a lot to ask for you stock coil packs. Have you stepped down to colder plugs??? Also if you were low on fuel then have a problem your always gonna wonder about the fuel filter. Not a bad idea to change it.

[3uromid]

Ko4's @ 26psi is a lot to ask for you stock coil packs. Have you stepped down to colder plugs??? Also if you were low on fuel then have a problem your always gonna wonder about the fuel filter. Not a bad idea to change it.

Have not stepped down to colder plugs. Will be testing coil packs tonight. The odd part is that I don't hear a misfire holding it at 2k or 3k when idling. Could the fuel filter be causing this? Choking it as specific bands?

[jimmer009]

coil packs can get "weak" before they go. I went with the 2.0 coil conversion cause I had one that would start to mis fire over 15psi. It really does not sound like your problem. Have you logged it lately??? Checking your injector duty cycle would be anther place to start

[christianb5s4]

If you haven't replaced something yourself, do NOT assume it was replaced before. Everyone should replace the fuel filter because it's one of the more neglected maintenance items on these cars and after doing a bunch of pulls it could have unseated some dirt or debris in the fuel system that clogged or partially clogged the filter.

However, start with the simple things like logging or checking the fuel filter before going into more complex or pricey stuff.

[3uromid]

coil packs can get "weak" before they go. I went with the 2.0 coil conversion cause I had one that would start to mis fire over 15psi. It really does not sound like your problem. Have you logged it lately??? Checking your injector duty cycle would be anther place to start

How can I check my duty cycle? I checked all the coil packs by pulling one off at a time and listening to see if they were causing any change in the system and all seem fine (idling). My fuel pump seems to be working fine as I could hear it whining (what seems to be normal) while I get on it (took out the back seat and pulled off the mat). Will be cleaning my fuel filter and seeing if this does anything...

I'm beginning to think it might be pre-detonation.

I just installed VAGCOM and scanned the engine. Received codes for running rich and misfire in cylinder 3. These were old codes. I scanned it again and went for a quick drive and no codes showed up except 1 unrelated (18058 - Powertrain Data Bus" Missing Message from Instrument Cluster).

[3uromid]

If you haven't replaced something yourself, do NOT assume it was replaced before. Everyone should replace the fuel filter because it's one of the more neglected maintenance items on these cars and after doing a bunch of pulls it could have unseated some dirt or debris in the fuel system that clogged or partially clogged the filter.

However, start with the simple things like logging or checking the fuel filter before going into more complex or pricey stuff.

I opened up the fuel pump and it looked dirty as hell. Will clean fuel filter most likely tomorrow.

[jimmer009]

To test the injectors duty cycle I use me7logger. I do a 3rd gear run 2000-6500 and then use ecuxplot to see the data. All the programs are over at nefmoto. But you really have to do a lot reading, and even then I needed help to get all up and going on my laptop. With vagcom its a pain but if you google you see it's just the first 3 measuring blocks

There should ppl here with ko4's. But I'm really thinking that 26psi out of those is far over stick injectors. I'm not sure about 440cc ones I think that would be close to there limit. Unless you wanted to run a 5 bar fpr. But then you might want to step up to an aftermarket fuel pump

[3uromid]

To test the injectors duty cycle I use me7logger. I do a 3rd gear run 2000-6500 and then use ecuxplot to see the data. All the programs are over at nefmoto. But you really have to do a lot reading, and even then I needed help to get all up and going on my laptop. With vagcom its a pain but if you google you see it's just the first 3 measuring blocks

There should ppl here with ko4's. But I'm really thinking that 26psi out of those is far over stick injectors. I'm not sure about 440cc ones I think that would be close to there limit. Unless you wanted to run a 5 bar fpr. But then you might want to step up to an aftermarket fuel pump

Thanks for the info. A bit invasive for me at this point although if all else fails will definitely check out the me7logger.

Changed spark plugs today (didn't gap but will be gapping to .25 -.28 is what I'm hearing is appropriate) but noticed on one of my old spark plugs the tip where the spark is given looks as if it has been chipped off. A buddy mentioned this could be from running lean? Issue is even worse with new spark plugs, which i'm assuming is because of not gapping them.

The sputtering is apparent at any boost now rather than only WOT.

Also, when revving in neutral a rev limiter is active not letting it pass 4500ish RPM's. Maybe this could lead to something?

[jimmer009]

The Rev limiter is probably antilag. If it's just at idle. And coil packs get worse like that. High boost then right down to all the time.

Do you have a pic of the chipped plug??? Any imperfections in the spark plugs could hurt it. But any clue where the chip off the plug could of gone?? Do you have access to a boarascope to look into the pisition???

Lean means hot. And I don't see this breaking off part of a plug. But I may be wrong. .28 is what they say for stock coil packs. But I am really happy with b7rke it at least worth a Google.

[blitz2190]

there is a stock 5k limiter on these engine if your not moving, also free reving an engine is not good nor is it a good diagnostic tool as there is no load on the engine. Sounds like one of your coils is going which will only show under boost when the air flow is strong enough to blow out weak spark, regap smaller and see if the problem gets better. Most likely time for a new coil or multiple. Personally I would dot the FSI swap but that depends on how good you are at wrenching, replace your fuel filter anyways as its cheap and trying to clean it will do nothing.

[Seerlah]

Why not log, see which cylinder(s) is misfiring, and go from there?

[Rod Ratio]

Gap those plugs to something remotely appropriate before further chasing your tail. .027